I've found this site very inspirational.
http://www.bulgarov.com/blackphoenix_10days_of_mech.html

Also, when I'm 'stuck' I typically jump into ArtStation or Pinterest for inspiration. Another good thing to try is to 'time-box' some quick studies. The idea being trying to build something quickly. These are two time-boxes (done in a couple hours) vaporizers I created in 3D Coat a couple months ago. It was a great learning process and I ended up with something I could show.